Strength determination and durability of load-bearing timber-glass-structures

In timber engineering, the combination with other materials in form of hybrid structures usually leads to stiffer and stronger, therefore more efficient structures [1]. The use of glass in timber construction is a promising combination of materials, which leads to functional and aesthetic products. Joining these two materials is made possible by the use of adapted adhesives, which ensure a load transfer with no mechanical weakening of the glass panels due to drill-holes. Furthermore, glass is a brittle material, and timber is able to achieve a certain redundancy of the structure [2]. Timber, glass and adhesive are materials differing in their mechanical properties, thermal expansion, hygroscopic adsorption and failure behavior; the differences in all these parameters have an influence on the long term durability of constructions. In order to shed light on the behavior of glass-timber compound under environmental loads, different strength determination methods were performed on small and large scale probes. The measurement to place after exposure to temperature (from -20 °C to +80 °C) and humidity(from 60% to 100% rel. hum.) Three different timber species were considered (spruce, beech and oak), and combined with float- and pre-stressed glass using different adhesives. The investigation outlines various aspects on what to consider when bonding wood and glass, and allows for a better understanding of this type of hybrid structural element.